Electrical devices such as electrical connectors typically have an electrical cord or cable extending outwardly from the device. It is necessary to securely fasten the electrical cord to the electrical device to prevent the electrical conductors from being pulled from their terminations, which can damage the conductors and the electrical device. If the electrical conductors are pulled or torn away from their terminations in the electrical device, this can result in the electrical device becoming inoperable, and in certain circumstances can result in serious injury to the user due to shorting of the electrical current being carried in the conductors.
Accordingly, corded electrical devices typically include a strain relief assembly for gripping and coupling the electrical cord or cable thereto, and for maintaining slack between the ends of the conductors and their respective terminals or electrical connections within the electrical device. Presently, there are a wide variety of strain relief assemblies available for electrical devices. For example, many electrical devices have a pair of cord clamping members for gripping and coupling the electrical cord thereto. Typically, one of the cord clamping members is stationary, while the other cord clamping member is movable in a direction substantially perpendicular to the longitudinal axis of the electrical cord. The clamping members may include a rib or a series of ribs for engaging the electrical cord to ensure a good grip on the electrical cord.
Examples of some prior electrical connectors having a strain relief assembly with a stationary clamp and a movable clamp are disclosed in the following U.S. Pat. Nos.: 3,393,395 to Hubbell; 3,784,961 to Gartland, Jr.; 3,904,265 to Hollydale et al; 4,080,036 to Hagel; 4,178,056 to Lee; 4,213,667 to Wittes; 4,931,023 to Browne; 5,217,389 to MacKay et al; 5,304,075 to Hoffman; and 5,338,222 to Boteler.
Examples of some other prior electrical connectors with internal strain relief are disclosed in the following U.S. Pat. Nos.: 3,437,980 to Smith; 3,856,376 to Poliak et al; 4,108,527 to Douty et al; 4,138,185 to Jaconette, Jr.; 4,208,085 to Lawrence et al; 4,561,715 to Sanchez; 4,721,483 to Dickie; 4,722,580 to Kocher et al; 4,749,369 to Wang; 4,921,441 to Sauder; 4,963,104 to Dickie; and 5,277,619 to Yamamoto.
One disadvantage with these prior art strain relief assemblies is that the electrical conductors of the electrical cord are gripped as a group. In other words, the clamping elements of the strain relief assembly directly engages the outer sheath of the electrical cord with the conductors bundled therein. The problem with gripping the sheath of the cord is that the sheath is typically constructed of a stretchable material. When an axial force is applied to the cord, the sheath can stretch and the conductors therein will slide beneath the sheath at the point of the clamping elements. If such sliding movement of the conductors occurs, then the ends of the terminals may pull out of their terminal connections.
In addition, some of the prior art strain relief assemblies increase the difficulty of assembling the electrical connectors. Moreover, some of these strain relief assemblies are difficult to manufacture and require special molding procedures which can significantly increase the total cost of the electrical connectors.
In view of the above, it is apparent that there exists a need for an electrical cord clamp for an electrical device or connector which will overcome the above-mentioned problems of the prior art devices. This invention addresses this need in the art along with other needs which will become apparent to those skilled in the art once given this disclosure.